Need Help With Stepper Drive

[jeffg]

Hi so many to choose from. I have some vexta steppers they are the same size as PV269 4 wire bipolor 440 oz/in but mine have a custom winding 4.4a 2.5v I have been looking at lots of drives but i am not sure what amp. rating i need? If i use a microstepping drive do the motors need the full 4.4a I have a 38v 10a unregulated power supply. Many of the cheaper drives are only 3a. Any info you can give my will be helpfull i am a nubie! Here are pics. of my steppers thanks.

[jeffs555]

You can run the motors at less than their rated current, but torque is directly proportional to current, so at 3 amps the static torque would be only 68% of what it would be with 4.4 amps. However, static torque is not usually the problem. Torque on any stepper drops off as speed increases. At some speed the torque will be so low that the motor starts losing steps. At a 3 amp setting, the torque will not drop as quickly with speed as it would with 4.4 amps. At some speed the torque will be the same whether the drive is set for 4.4 amps or 3 amps.

[Konstantin]

You wont have to worry about the amperage if you choose to go with a chopped drive, just configure the chopper for 4.4A. Microstepping does not force you to use rated current (imho) it just smooths the motor rotation at low speeds. Your PSU will be barely enough for 2 motors like that.

Are you sure the motor holding torque is 440 oz/in? Imho it looks too small or your hand is really huge , I would guess its about 200ish.

Do you want to make your own drives following a free design or to purchase already made ones?
I dont recall that we have bipolar drives for +3A here on the zone, at least Pminmo has none of that rating, you look at his web at www.pminmo.com.

What is your idea for that motor? Do you have a design for your mill/router/lathe ?


Konstantin.

[jeffg]

Thanks for the info.I guess my hand is pretty big? I got the steppers on ebay they are 60mm x85mm the only size that match at vexta is pv269 they are 440 oz/in I called vexta the tech. said it was a custom winding and if i could supply full amps my motors would have more torque than a stock pv269.On the psu it was a 24v 18a regulated i removed the regulating board and now i get 38.9v at the capacitor i am not sure what the amps are at 38v?I might have to upgrade to a bigger psu? I am building a 4x8 router table [my 2nd] The 1st table has poor preformance.I want to get the best preformance for the least$$$on the new one.I was thinking about keling drives? I am posting pics. of table,psu and pv269 specs. tell me what you think ?

[Konstantin]

Looks interesting.
Have you measured the impedance of the stepper coils?

Konstantin.

[jeffg]

No sorry i am not good with electronics this is all new to me thats why i need help. i dont want to make a costly mistake.